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United States Patent |
6,007,959
|
Matsuoka
,   et al.
|
December 28, 1999
|
Method for making an image from a material comprising resin particles
and recording component held inside the resin particles
Abstract
An image forming material which comprises fine resin particles and a
recording component held inside the fine resin particles. The recording
component comprises a colorant and water, and the fine resin particles
can, when supplied with an electric energy, release the recording
component held inside. The image forming material is brought into contact
with a latent image holding body on which a latent image has been formed.
Then an image is produced by applying an electric energy on the image
forming material for the liquefaction thereof to wet and develop the
latent image on the latent image holding body with the recording component
contained in the image forming material.
Inventors:
|
Matsuoka; Hirotaka (Minami-Ashigara, JP);
Lee; JongWon (Minami-Ashigara, JP)
|
Assignee:
|
Fuji Xerox Co., Ltd. (Tokyo, JP)
|
Appl. No.:
|
731911 |
Filed:
|
October 22, 1996 |
Foreign Application Priority Data
Current U.S. Class: |
430/118; 347/264 |
Intern'l Class: |
G03G 009/08 |
Field of Search: |
347/264
346/140.1
523/161,200,201,202,203,204,205
430/138,118
|
References Cited
U.S. Patent Documents
4470055 | Sep., 1984 | Todoh | 346/140.
|
4565764 | Jan., 1986 | Nakahara et al. | 430/111.
|
5209998 | May., 1993 | Kavassalis et al. | 430/106.
|
5529873 | Jun., 1996 | Chiba et al. | 430/109.
|
Foreign Patent Documents |
57-29460 | Feb., 1982 | JP.
| |
57-29460 | Dec., 1982 | JP.
| |
62-60690 | Mar., 1987 | JP.
| |
1-110971 | Apr., 1989 | JP.
| |
1-136763 | May., 1989 | JP.
| |
1-136761 | May., 1989 | JP.
| |
1-136762 | May., 1989 | JP.
| |
4-296587 | Oct., 1992 | JP.
| |
Primary Examiner: Fuller; Benjamin R.
Assistant Examiner: Annick; Christina
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
What is claimed is:
1. A method for making an image, comprising the steps of:
providing a latent image holding body on which a latent image is formed;
providing an image forming material that is virtually a solid and is
converted into a liquid when supplied with an electric field; and
converting the image forming material into a liquid by the application of
the electric field and wetting and developing the latent image on the
latent image holding body with a recording component contained in the
image forming material.
2. The method of claim 1, wherein the image forming material comprises
resin particles and the recording component, the recording component
comprising a colorant and a solvent, and wherein the recording component
is held inside the resin particles and wherein the resin particles can, by
the application of an electric field, release the recording component to
liquefy the image forming material.
3. The method of claim 2 wherein the image forming material further
comprises a response accelerator.
4. The method of claim 2 wherein the resin particles are made of a resin
that has a three-dimensionally cross-linked structure derived from at
least one of an acrylamide derivative monomer and an acetamide derivative
monomer.
5. The method of claim 2 wherein the solvent that is an ingredient of the
recording component is water.
6. The method of claim 1 wherein the image forming material comprises resin
particles and the recording component is held inside the resin particles,
wherein the recording component comprises a colorant and a solvent, wherein
the resin particles are virtually a solid at room temperature and can, by
the application of an electric field, be converted into a liquid to
release the recording component, wherein the resin particles are made of a
resin that has a three-dimensionally cross-linked structure derived from
at least one of an acrylamide derivative monomer and an acetamide
derivative monomer; and
wherein the solvent is water.
7. The method of claim 1 wherein an electrostatic attraction force which
acts between the latent image on the latent image holding body and the
recording component of the image forming material, is increased
selectively in the area corresponding to the latent image, and the latent
image is wetted and developed with the recording component contained in
the image forming material.
8. The method of claim 1 wherein the image forming material is recharged
with recording component so that the image forming material can be reused
to repetitively form the image.
9. The method of claim 1 wherein the developed image is transferred to a
sheet of recording paper.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention related to a novel image forming material based on a
material, the fluidity of which varies by the application thereon of an
electric energy, and to a method for making an image by using the
material.
2. Description of Related Art
In wet development processes for electrostatic photographs, almost all of
the carrier liquids which have been hitherto proposed for wet development
are organic solvents having high vapor pressures. Therefore, problems
common to these processes are as follows: (1) Treatment of the carrier
liquid vapor discharged is necessary at, for example, the time of fixing
operation; (2) Some of the carrier liquids are inflammable; and (3) After
the fixing treatment on such a substrate as paper, residual solvents in
the substrate gradually evaporate and the copies generate the odors of the
solvent. As a result, these processes cannot satisfactorily meet the
recent requirements for environmental conservation.
As a means to avoid the above-mentioned problems, proposed are wet-process
developers which are mainly composed of water or a water-soluble solvent
that is safe and harmless to office environments and humans and developing
methods using the same, such methods as wetting development, flight
development, suction development, ink mist development and two-step
development, which involve utilizing electroconductive developers.
Of these development methods proposed hitherto, one developing method where
a photosensitive body and a developer liquid comes into direct contact
with each other, makes it impossible to avoide the smearing of image and
the adhesion of the liquid to the entire surface of paper because the
developer wets the entire surface of the photosensitive body. A
non-contact development system causes, in addition to the above-mentioned
smear problem, an undesirable suction of a wet developer into the
periphery of image, with the result that the fogging of the image and the
bleeding at the fine lines of the image are not avoided. And, none of the
development methods of prior art have provided satisfactory quality of
image.
To solve these technical problems, one of the measures that have been
proposed hitherto is the application of a molecular gel which causes a
phase transition by such influencing factors as temperature, solvent
composition, pH, ion concentration and electric field.
Details of molecular gels are described, for example, in "Materials having
molecular functions and development of elements, Chapter 2, Elements" by
the supervision of Takao Shimizu (published by NTS in 1994). Technical
literatures other than this also provide the descriptions suggestive of
the possibility that above-mentioned phenomenon may be utilized for a
sensor, an actuator and a reactor, conversion elements for converting
chemical energy into mechanical energy, artificial muscle, a display and a
marking device.
For example, Japanese Patent Application Laid-Open (JP-A) Nos. 62-60,690
and 01-110,971 describe a direct marking process comprising the steps of
directly supplying current to a gel by means of pattern-shaped, voltage
applying electrodes to form an adhesive sol of ink and transferring the
ink. Japanese Patent Application Laid-Open (JP-A) Nos. 01-136,761,
01-136,762 and 01-136,763 describe a direct marking process comprising the
steps of sandwiching a gel between an absorbent membrane and a porous
material held on an electroconductive substrate and supplying a current to
the foregoing combination to discharge an ink, which will be transferred
to paper through the porous material. None of these proposals has not been
put into practice because of the problem of response speed to the volume
change of the gel and of the stability at the time of repetitive use.
SUMMARY OF THE INVENTION
Accordingly, the first object of the present invention is to provide a
novel image forming material that improves the response speed and
stability problems, which are disadvantages of the above-mentioned
electroconductive wet-process developers, and that can provide a good
image quality free of the fogging of image and the bleeding of the fine
lines of image as well as of the smearing of the image.
The second object of the present invention is to provide a method for
making an image by a wet process utilizing a novel image forming material
that enhances the response speed and improves the stability and that
enables the high-speed manufacture of prints utilizing a photosensitive
body.
The present inventors have accomplished the invention based on the
discovery that by means of a polymeric gel-based developer comprising fine
resin particles which, when supplied with electric energy, releases the
liquid that has been held inside and absorb the liquid when not supplied
with the electric energy, a recording component comprised of a colorant, a
solvent such as water or water-soluble solvent and optionally a response
accelerator, only an electrostatic latent image is selectively wetted, for
development, with the released recording component, to solve the
aforementioned problems thus providing repeatedly a good image free of
bleeding, and based on making it sure that the foregoing method can be
applied to an ordinary electrophotographic process.
Accordingly, the present invention relates to an image forming material
comprising fine resin particles and a recording component held inside
them, wherein the recording component comprises a colorant and a solvent
and wherein the fine resin particles can, by the application of an
electric energy, release the recording component held inside them.
According to the image forming material of the present invention, the
response speed and stability, which are the problems of the conventional
electroconductive wet developers, are improved and a good image quality,
free of the fogging of image and the bleeding of fine lines of the image
as well as of the smearing of the image, can be obtained in a stable
manner.
The image forming material comprises resin particles that hold a recording
component inside them, and is characterized in that virtually the material
is a solid at room temperature which, when impressed with an electric
energy, is converted into a liquid. Besides, it is preferred that the
particles further contain a response accelerator.
Preferably, the fine resin particles are made of a resin that has a
three-dimensionally cross-linked structure derived from an acrylamide
derivative monomer and/or an acetamide derivative monomer. An average
particle size of the fine resin particles, when they contain the recording
component, is in the range of 0.1 to 100 .mu.m.
Preferably, the solvent which is an ingredient of the recording component
is water, and the response accelerator is selected from the group
consisting of a polar solvent, a solid electrolyte and a surface active
agent.
The method for making an image according to the present invention comprises
the steps of providing a latent image holding body on which a latent image
has been formed; providing an image forming material that is virtually a
solid at room temperature and is converted into a liquid when supplied
with an electric energy; and applying an electric energy onto the image
forming material to be liquefied, thereby wetting and developing the
latent image on the latent image holding body with the recording component
contained in the image forming material.
The method for making an image according to the present invention enables
the response speed and stability improved, and the high-speed manufacture
of prints utilizing a photosensitive body.
Preferably the method for making an image according to the present
invention increases the electrostatic attraction force which acts between
the electrostatic latent image on the latent image holding body and the
recording component of the image forming material, selectively in the area
corresponding to the electrostatic latent image, and permits to wet and
develop the electrostatic latent image with the recording component
contained in the image forming material.
The electric energy to be applied is preferably selected from the
electrostatic latent image, electric field of direct current and direct
current corresponding to image information.
The electric energy may be from 0.01 to 50 V/.mu.m, preferably 0.1 to 10
V/.mu.m. Energy applying time is preferably from 0.01 to 5 sec.
In the method for making an image according to the present invention,
preferably images are produced in a repetitive manner by supplying a
recording component to the image forming material.
In the image forming material according to the present invention, owing to
the fine resin particles which, when supplied with an electric energy,
release the liquid that is held inside them and, when not supplied with an
electric energy, absorb the liquid, it is possible to control
electroconductivity-related phenomena, such as fluidity, adhesiveness,
electrostatic attraction force toward the latent image of the
photosensitive body and wettability of the developer facing the latent
image of the photosensitive body that is image information, by adjusting
the electric energy. As a result, it is possible to sufficiently enhance
the electrostatic attraction force or adhesion to the latent image of the
photosensitive body in image areas, and to nullify or sufficiently lower
the electrostatic attraction force or adhesion in non-image areas, thus
enabling to obtain a good image.
More specifically, the image forming material is provided with the
electrostatic latent image, electric field of direct current or direct
direct current corresponding to image information to cause the release of
the recording component comprising a colorant and a solvent such as water
thereby increasing the attraction force or adhesion to the latent image.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatically shown cross-sectional view illustrating an
apparatus for making an image.
FIG. 2A is an enlarged cross-sectional view illustrating the contact area
between a developer holding roll and a photosensitive body of the
apparatus for making an image of FIG. 1, wherein the developer holding
roll has a smooth surface.
FIG. 2B is an enlarged cross-sectional view similar to FIG. 2A except that
a developer holding roll is used which has an irregularity on the surface.
FIG. 3 is a conceptual view illustrating an apparatus for evaluating
electric field-induced shrinkage, to measure the viscosity of the image
forming material of the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
The present invention will be explained in detail below.
The fine resin particles which are used in the image forming material of
the present invention, preferably have a three-dimensional, cross-linked
structure derived from a monomer selected from the group consisting of an
acrylamide derivative and an acetamide derivative. From the viewpoint of
the improvement of response speed and of the capability of repeated use in
an ordinary electrophotographic process, the adding amount of any one type
of the fine resin particles is usually in the range of not more than 50
percent by weight, preferably in the range of 0.1 to 10 percent by weight,
based on the total weight of the image forming material.
Generally, the image forming material of the present invention consists
essentially of 3 to 4 constituents that are described below in detail. The
wording "consists essentially of" means that any component which does not
impedes advantages of the developer, is not excluded from the composition.
For example, additional constituents, utilized in a well-known developer,
may be present which include finely divided metal oxides, metal soaps,
fine resin particles, physical property adjusting agents and other
auxiliary materials. The above-mentioned 3 or 4 components are fine resin
particles, a dye or a pigment as a colorant, a solvent such as water or
organic solvent for dispersing the foregoing components, and optionally a
response accelerator.
The fine resin particles, which is used in the present invention to release
the liquid that is held in the resin when an electric energy is applied,
are a polymeric gel having a small particle size. For this purpose, usable
are a well-known heat-responding gel having a small particle size and a
gel whose volume changes depending on the concentration of proton.
A suitable example of material that forms the fine resin particles is a
three-dimensionally crosslinked polymer made from monomers which include
acrylamide and an N-substituted acrylamide derivative having a lower alkyl
or alkylene radical introduced into the amide group, or otherwise
acetamide and an N-substituted acetamide derivative. The weight average
molecular weight is preferably from 10.sup.3 to 10.sup.5.
Examples of the acrylamide derivatives include N-acrylamide,
N-ethylacrylamide, N,N-diethylacrylamide, N-methyl, N-ethylacrylamide,
N-isobutylacrylamide, N,N-diisopropylacrylamide, N-isobutylacrylamide,
N-cyclohexylacrylamide, N-phenylacrylamide, N-benzylacrylamide and
N-isopropyloxyacrylamide. Besides, examples of the acetamide derivatives
include N-vinylacetamide, N-vinylisobutylamide and N,N-diisobutylamide.
Examples of the monomers which can be copolymerized with the
above-mentioned acrylamide-based monomers or acetamide-based monomers and
which are non-polar or polar, include acrylic acid, an acrylic acid ester,
acrylonitrile, styrene, vinylacetate, maleic acid ester, acrolein,
1,2-dimethyl-5-vinylpyridinium methyl sulfate, methacylamide, N-methylol
acrylamide, 2-methyl-5-vinylpyridine, sodium vinylsulfonate and vinylidene
chloride.
Examples of the monomers which can be used for crosslinking the
above-mentioned acrylamide-based monomers or acetamide-based monomers,
include N, N'-methylene bisacrylamide, ethylene glycol dimethacrylate,
glycerin triacrylate and divinyl benzene.
The fine resin particles may be produced by any of known polymerization
methods which include emulsion polymerization, reverse-phase suspension
polymerization, precipitation polymerization and dispersion
polymerization.
Examples of an initiator which can be used in an aqueous solvent system,
include ammonium sulfate-sodium hydrogensulfate and hydrogen
peroxide-Fe(I). Examples of an initiator, which can be used in a
nonaqueous solvent system, include azoisobutylonitrile, cumene
hydroxyperoxide and azobiscyclohexane carbonitrile.
As the fine resin particles, polymeric gels can also be used which have
been hitherto known as heat-sensitive gels and which are made from
monomers such as styrene sulfonic acid, 2-acrylamide-2-methylpropane
sulfonic acid and trimethyl(N-acrylol-3-aminopropyl)ammonium chloride. In
addition, usable in the present invention are amino-containing polymeric
gels comprising amine or acrylamine, which exhibit volume change depending
on the change of the concentration of proton or on the change of ion or
solvent composition, as well as copolymers of polyvinyl alcohol and
acrylic acid.
When an image forming material is prepared from these fine resin particles
together with the recording component comprising a colorant and a solvent,
the resin particles hold the recording component inside them and are
virtually in a solid state. When supplied with an electric energy, they
release the recording component that has been held therein. When
macroscopically observed, the above-described function can be supported by
a phenomenon that a substance which is virtually a solid at room
temperature is converted into a liquid by the application of an electric
energy.
That is, according to an embodiment of the present invention, the image
forming material is virtually a solid at room temperature and is converted
into a liquid having a viscosity of not greater than 10.sup.4 mPas by the
application of an electric energy. Therefore, when, for example, the
electrostatic attraction force generated between an electrostatic latent
image on a photosensitive body and the recording component is increased
selectively only on the area that corresponds to an image area, the
recording component on the area that corresponds to the image is released
as a liquid to selectively wet the above-mentioned area alone, with the
released recording component. As a result, an image making process is
effected. The area which corresponds to the non-image area and to which no
recording component is released, is not colored, thus leading to an
excellent quality of image.
The sizes of the fine resin particles, which may depend on their volume
change ratios, are in the range of 0.1 to 100 .mu.m, preferably 0.1 to 20
.mu.m, when they are not supplied with an electric energy, that is, they
hold the recording component. The fine resin particles the sizes of which
exceed 100 .mu.m undesirably lower the response speed of the gel, whereas
the fine resin particles the sizes of which are less than 0.1 .mu.m have
an insufficient holding amount of the recording component and poor
handling property.
The fine resin particles having the desired particle sizes may be prepared
by adjusting the synthesis condition thereof. In addition, the gel
polymers obtained by synthesis and drying may be subjected to a known
pulverizing procedure such as pulverizing in gas stream, pulverizing in
frozen state or impacting.
The second constituent of the image forming material of the present
invention is a dye or a pigment as a colorant. The colorant may be
selected from known dyes and pigments provided that they have desired
properties including durability. These dyes and pigments may be used alone
or in a combination of two or more of them.
The water-soluble dyes that can be used as a colorant are those which are
indicated as acid dyes, direct dyes, basic dyes, reactive dyes and food
dyes in Color Index and which have excellent water resistance and light
fastness. Examples of usable dyes include C.I. Acid Yellow 17, 23, 42, 44,
79, 142; C.I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87,
89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289; C.I. Acid Blue 9,
29, 45, 92, 249; C.I. Acid Black 1, 2, 7, 24, 26, 94; C.I. Food Yellow 3,
4; C.I. Food Red 7, 9, 14; C.I. Food Black 2; C.I. Direct Yellow 1, 12,
24, 26, 33, 44, 50, 86, 142, 144; C.I. Direct Red 1, 4, 9, 13, 17, 20, 28,
31, 39, 80, 81, 83, 89, 225, 227; C.I. Direct Orange 26, 29, 62, 102; C.I.
Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165,
199, 202; C.I. Direct Black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154,
168; C.I. Basic Yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29,
32, 36, 40, 41, 45, 49, 51, 53, 63, 67, 70, 73, 77, 87, 91; C.I. Basic Red
2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52,
54, 59, 68, 69, 70, 73, 78, 82, 102, 104, 109, 112; C.I. Basic Blue 1, 3,
5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 69, 92, 93, 105, 117, 120, 122,
124, 129, 137, 141, 147, 155; C.I. Basic Black 2, 8.
As for pigments, examples of organic pigments include azo-based,
phthalocyanine-base, anthraquinone-based, quinacridone-based,
dioxadine-based, indigo-based, thioindigo-based, perylene-based,
isoindolenone-based, aniline black based and azomethylene-based.
Meanwhile, inorganic pigments include ultramarine blue, cadmium yellow,
iron oxide, chromium yellow, titanium oxide and carbon black.
As colorants, besides the above-mentioned ones, also usable are colored
polymers and oil-soluble dyes containing wax, and, also usable are silica,
colloidal silica, metal oxides, such as aluminum oxide, magnetite or
ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide,
titanium oxide and magnesium oxide as well as mixtures thereof.
When pigments are used as a colorant, pigment dispersing agents may be
used, as necessary. Examples of pigment dispersing agents include
naturally occurring hydrophilic polymers, such as vegetable polymers such
as gum arabic, tragacanth gum, guar gum, calaya gum, low cast bean gum,
arabino galacton, pectin, queen's seed starch, mannan alginic acid,
caraginan and agar, animal polymers such as gelatin, casein, albumin and
collagen, microoganism-derived polymers such as xanthene gum, dextorin,
succinoglukan and curdlan, semi-synthesized polymers, such as fibrous
polymers including methyl cellulose, ethyl cellulose, hydroxyethyl
cellulose, hydroxypropyl cellulose and carboxymethyl cellulose,
starch-based polymers including starch glicolic acid sodium salt and
starch phosphoric acid ester sodium salt, alginic acid-based polymers
including alginic acid sodium salt and alginic acid propylene glycol
ester, fully synthesized polymers, such as vinyl polymers including
polyvinyl alcohol, polyvinyl pyrrolidone and polyvinyl methy ether,
acrylic resins including non-crosslinked polyacrylamide, polyacrylic acid
and alkali salts thereof and water-soluble styrene/acrylic resins,
water-soluble styrene/maleic acid resins, water-soluble
vinylnaphthalene/acrylic resin, water-soluble vinylnaphthalene/maleic
acid, alkali metal salts of .beta.-naphthalene sulfonic acid-formalin
condensation products, polymeric compounds having pendant salts of
cationic functional groups such as quaternary ammonium and amino groups,
and naturally occurring polymers including shellac.
The concentration of the colorant may be from 0.1 to 50%, preferably from 1
to 10% by weight of the polymer material, and from 0.1 to 20, preferably
from 1 to 10% by weight of the image forming material.
The third constituent of the image forming material of the present
invention is a solvent in which a colorant, i.e., dye or pigment, is
dispersed. Although the main solvent is water, any of the following
compounds, which function as a moisture holding agent and the like, may be
added to the image forming material in order to prevent the coagulation
due to evaporation of water from the dispersed fine particles and coloring
materials. Examples of such compounds include monohydric alcohols, such as
ethanol, methanol and propanol, polyhydric alcohols, such as ethylene
glycol, diethylene glycol, triethylene glycol, tetraethylene glycol,
polyethylene glycol, propylene glycol, dipropylene glycol, glycerin,
low-molecular-weight polyethylene glycol and hexylene glycol, alkyl ethers
of polyhydric alcohols, such as ethylene glycol monobutyl ether,
diethylene glycol monomethyl ether, triethylene glycol monomethyl ether,
tetraethylene glycol monomethyl ether, ethylene glycol monomethyl ether
and propylene glycol monoethyl ether, aryl ether of polyhydric alcohols,
such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl
ether, nitrogen-containing heterocyclic compounds, such as
N-methyl-2-pyrrolidone, 1,3-dimethyl imidazolidinone,
.epsilon.-caprolactam and .gamma.-butyrolactone, amides, such as
formamide, N-methyl formamide and N,N-dimethyl formamide, amines, such as
monoethanol amine, diethanol amine, triethanol amine, monoethyl amine,
diethyl amine and triethyl amine, sulfur-containing compounds, such as
dimethyl sulfoxide and sulfolane, propylene carbonate, and ethylene
carbonate. A single compound or a combination of two or more of the
compounds may be used together with water as a mixture.
The solvent may be used in an amount of from 1 to 80%, preferably from 1 to
20% by weight of the image forming material.
A surface active agent may be added to the recording component for
adjusting the surface tension thereof. As the surface active agent, use
may be made of a variety of surface active agents which include anionic,
cationic, nonionic and amphoteric. These may be used alone or in a
combination of two or more. The examples of anionic surface active agents
include alkylbenzene sulfonic acid salts, the examples of cationic surface
active agents include alkyl dimethyl ammonium salts, the examples of
nonionic surface active agents include polyoxyethylene derivatives such as
a polyethylene glycol alkyl ether and a higher alcohol ester of sugar, and
the examples of amphoteric surface active agents include
sulfobetaine-based types and amino acid-based types.
Besides, when necessary, various other agents can also be used which
include a pH buffer, a dye dissolving agent, a viscosity controller, such
as ammonium hydroxide, sodium hydroxide, urea, gum arabic or polyvinyl
alcohol, and a biocide, and antifungal agent.
In order to provide a preferred embodiment of the present invention, the
above-mentioned three main components are used together with a response
accelerator, which has the function to facilitate, when a current is
applied, the release of the liquid held inside the fine resin particles.
This function can also be performed by polar solvents, such as alcohol and
acetone that are used as a solvent, and by surface active agents
incorporated in the recording component. In addition, the compounds that
are usable as a response accelerating agent include a variety of solid
electrolytes. Examples of the solid electrolytes include potassium
chloride, sodium chloride, potassium iodide, sodium iodide, potassium
thiocyanate, potassium bromide, sodium bromide, tetraethyl ammonium
bromide, LiBF.sub.4, KPF.sub.6 and NaClO.sub.4 as well as alkyl sulfate
ester salts, lauryl sulfate salts, higher alcohol sulfate salts,
succinates, carboxylates, polyethylene glycol ether sulfate ester salts,
amide sulfuric acid salts, disulfonic acid salts, polyoxyethylene lauryl
ether sulfate salts, polyoxyethylene alkyl ether acetate, alkylphosphates,
polyoxyethylene alkyl ether phosphates, alkyl ammonium salts, alkylbenzyl
ammonium salts, perfluoroalkylammonium salts, perfluoroalkylsulfonate
salts, carboxylic acid salts, and phosphoric acid esters. The adding
amount of the electrolyte as a response accelerating agent is in the range
of 0.0001 mole/liter (of a solvent) to a saturated solubility and
preferably in the range of 0.005 mole/liter to a saturated solubility. An
amount of the electrolyte less than 0.0001 mole/liter brings about no
effect in the acceleration of the response speed, whereas an amount
exceeding the saturated solubility undesirably makes the system
heterogeneous.
Below, the method for making an image by use of the image forming material
is described in detail. An apparatus for making an image by use of the
image forming material of the present invention comprises a
light-transmissive electroconductive layer over a light-transmissive
support and a light source that irradiates light from the side of the
support.
FIG. 1 is a schematically illustrated cross-sectional view of an apparatus
for making an image by use of the wet developer of the present invention.
An apparatus for making an image 10 comprises a drum-shaped photosensitive
body 22, which is made by laminating a light-transmissive
electroconductive layer 18 and a photoconductive layer 20 onto a
light-transmissive support 16, an LED head 24 as a light source placed
within the drum-shaped photosensitive body 22, a developer feeding chamber
26 positioned under the photosensitive body 22 and a transfer roll 28
which faces the side of the photosensitive body 22. The LED head 24 is
positioned opposite the developer feeding chamber 26 via a part of the
photosensitive body 22. The developer feeding chamber 26 is equipped, for
example, with a developer feeding roll 30, a developer holding roll 32
positioned opposite thereto and a developer layer adjusting roll 34 that
abuts against the developer holding roll 32 so that the image forming
material (developer) 40, which has been stored in the developer feeding
chamber 26, is applied on the developer holding roll 32 with the roll 30
to be transferred to the outer periphery of the photosensitive roll 22
after being adjusted to a desired thickness of layer by means of the
developer layer adjusting roll 34.
Between the developer holding roll 32 and the light-transmissive
electroconductive layer 18, there is positioned a bias electric power
source 36 to supply both of the foregoing with a voltage that corresponds
to the property of the potential of the photosensitive body 22. In
addition, a means (not shown) of rotating the photosensitive body 22 is
also provided.
As the substrate which constitutes the developer holding roll 32, such
materials as iron, nickel, aluminum, copper, stainless steel and platinum
are utilized in pure form or after being vacuum deposited, for example,
with polyimide, if necessary. The surface of the developer holding roll 32
may be smooth as shown in FIG. 2A or may be provided with pyramid-shaped
fine irregularity that resembles a gravure roll as shown in FIG. 2B. The
fine irregularity may be in the configuration of a grid or of slant lines.
FIG. 2 is an enlarged cross-sectional view illustrating the contact area
between the developer holding roll 32 and the photosensitive body 22. On
the surface of the developer holding roll 32, there is provided a layer of
the developer 40 which is brought into contact with the surface of the
photosensitive body 22 so that a layer of the recording component which is
to be released from the resin particles in response to the application of
the voltage, will be provided on the surface of the photosensitive body
22.
The materials usable for the light-transmissive support 16, which are used
for the electrophotographic photosensitive body 22 that has at least a
light-transmissive electroconductive layer 18 and a photoconductive layer
20 and that is capable of back-light recording, include transparent
inorganic materials, such as glass, quartz and sapphire, and transparent
organic resins such as fluorocarbon resins, polyesters, polycarbonates,
polyethylene terephthalates, acrylic resins, polyimides and epoxy resins.
The materials usable for the light-transmissive electroconductive layer 18
may be transparent electroconductive materials which include ITO, tin
oxide, zinc oxide, lead oxide and indium oxide. As illustrated, an
amorphous silicon-based photoconductive layer 20, as a photosensitive
layer, may be laminated.
Besides the LED head 24, laser, liquid crystal shutter, halogen lamp, EL
array and the like can also be used as the light source.
Turning to FIG. 1, light exposure is performed while a direct current
voltage is applied between the light-transmissive support 16 and the
developer holding roll 32. An electric current signal, which is induced by
the difference of electroconductivities of bright and dark conditions of
the amorphous silicon-based photoconductive layer 20, causes the fluidity
of the developer 40, to which the current has been applied, to be chagned.
That is, the fine resin particles release the recording component. By
means of an electrostatic attractive force or by an electrical capillary
phenomenon or the like, the released recording component moves to the
electric latent image on the photosensitive body 22 to selectively wet the
latent image alone.
A recording paper 42, which has been fed from a paper feeding roll, is
inserted between the photoconductive layer 20 and a backup roll 28 so that
the recording component is transferred from the photoconductive layer 20
to the recording paper 42. The paper, which has the transferred recording
component, is then subjected to a fixing treatment.
When direct current electric voltage is applied between the developer
holding roll 32 and the light-transmissive electroconductive layer 18, the
light-transmissive electroconductive layer is made an anode in the case
where the fine resin particles shrink in an acidic environment, whereas
the light-transmissive electroconductive layer is made a cathode in the
case where the fine resin particles shrink in an alkaline environment.
Besides, the image making operation can be continued in a repeated manner
by supplying the image forming material 40 to the developer feeding
chamber 26.
EXAMPLES
Below, the present invention will be further explained by way of examples
and comparative examples. Although the following examples and comparative
examples provide the embodiments of the present invention, the present
invention is not limited to them. "Part" means "part by weight" and "%"
means "weight percent" in the example and comparative examples, unless
otherwise specified.
Example 1
(1) Preparation of fine resin particles and an image forming material
The fine resin particles which were used in the present invention were
prepared in the following manner.
______________________________________
1. Acrylamide 82 parts
2. Sodium acrylate 15 parts
3. N,N-methylene bisacrylamide *1 2 parts
4. Tetramethylethylenediamine *2 1 part
______________________________________
(*1: crosslinking agent, *2: polymerization promoter)
The above monomers were dissolved in 140 ml of water. An ammonium
persulfate solution, which had been prepared by dissolving 0.1 part of
ammonium persulfate in 1 ml of water, was combined with the
above-described monomer solution and the resulting solution was vigorously
stirred. The solution thus prepared was dripped into a solution comprising
75 ml of toluene, 25 ml of carbon tetrachloride in 1 ml of sorbitan
trioleate, and the resulting solution was vigorously stirred in an
atmosphere of nitrogen. After being stirred for 90 minutes at room
temperature, 100 ml of hexane was added to the solution and the solution
was stirred again. The solution separated into two layers, the aqueous
layer of which was collected. 100 ml of hexane was added to the aqueous
solution and the solution was washed under agitation. This washing
operation was repeated three times. After the last wash, the hexane was
evaporated by means of an evaporator, and a slurry gel was obtained. The
gel was washed with water and acetone alternately and then the solvents
were completely evaporated by means of a vacuum drying apparatus to obtain
a dry gel polymer. The powdery gel was comminuted by use of Meteor Rotary
Mill LA-P0 (available from Ito Manufacturing Co., Ltd.) to obtain gel
polymer powder with a peak particle size of about 10 microns. This powder
was dispersed in a 10% acetone aqueous solution and the dispersion was
held in a sufficient equilibrium.
Next, Carmin 6B, a colorant (available from Dainichiseika Color & Chemical
Mfg. Co., Ltd.), which had been admixed with a 10% acetone aqueous
solution was charged into 01 Attritor (available from Mitsui Miike
Machinery Co., Ltd.) and were subjected to milling of about 20 hours by
use of steel balls having a diameter of 0.8 mm, at a rotor speed of 300
rpm, to prepare a pigment dispersion. This pigment dispersion was
dispersed into the aforementioned gel. Finally, the resulting dispersion
was admixed with 5 ml of 4% KCl aqueous solution, as a response
accelerator, and thus a slurry image forming material (developer) was
prepared.
(2) Viscosity measurement of the developer after the application of an
electric energy
The developer, which had been prepared in the above-described manner, was
placed in an apparatus for evaluating an electric field-induced shrinkage
to measure its viscosity. The apparatus for evaluating the electric
field-induced shrinkage 50 comprises two sheets of transparent glass 54,
each having a light-transmissive electroconductive layer 52 on the
surface, which are spaced apart by an insulating spacer 56. An electric
power source 58 is provided to supply a direct current voltage between the
two light-transmissive electroconductive layers 52.
The developer 40 was placed in the apparatus for evaluating the electric
field-induced shrinkage 50 and an electric field of 0.40 V/.mu.m was
applied between the light-transmissive electroconductive layers (ITO
layers) 52 for one second. Then, the recording component oozed from the
developer 40, and was collected and the viscosity measurement was
conducted. The viscosity was measured at a shear rate of 1,400 sec.sup.-1
and the results are shown in Table 1.
(3) Method for the evaluation of image and the stability in repetitive use
The obtained developer was placed in the recording apparatus of FIG. 1. An
image was formed on the photosensitive body by carrying out the exposure
according to the condition, i.e., wavelength: 660 nm and light exposure
amount: 0.4 J/cm.sup.2, while applying a voltage of +100 V between the
developer holding roll and the light-transmissive electroconductive layer.
The image was transferred to a sheet of recording paper. The transferred
image was clear and free of bleeding and fogging of the background.
Further, image on 3,000 A4 size papers were prepared consecutively at a
rate of 60 images per minute in the direction of length of A4 size. After
that, respective images were evaluated in the same manner to find entirely
no deterioration of the image.
Example 2
The fine resin particles of the following composition were prepared. A
recording component to the fine resin particles were added thereto, to
obtain an image forming material. The image forming material was subjected
to the evaluation of the image, viscosity measurement and evaluation of
the stability of image in repetitive use in the same manner as in Example
1.
(1) Preparation of fine resin particles and image forming materials
The fine resin particles were prepared in the following manner.
______________________________________
1. Acrylamide 82 parts
2. 2-acrylamide-2-methylpropane sulfonic acid 15 parts
3. N,N-methylene bisacrylamide *1 2 parts
4. Tetramethylethylenediamine *2 1 part
______________________________________
(*1: crosslinking agent, *2: polymerization promoter)
The above monomers were dissolved in 140 ml of water. An ammonium
persulfate solution, which had been prepared by dissolving 0.1 part of
ammonium persulfate in 1 ml of water, was combined with the
above-described monomer solution and the resulting solution was vigorously
stirred. The solution thus prepared was dripped into a solution comprising
75 ml of toluene, 25 ml of chloroform and 1 ml of sorbitan trioleate, and
the resulting solution was vigorously stirred in an atmosphere of
nitrogen. After being stirred for 90 minutes at 70.degree. C., 100 ml of
liquid paraffin was added to the solution and the solution was stirred
again. The solution separated into two layers, the aqueous layer of which
was collected. 100 ml of liquid paraffin was added to the aqueous solution
and the solution was washed under agitation. This washing operation was
repeated three times. After the last wash, the liquid paraffin was
evaporated by means of an evaporator, to obtain a slurry gel. The gel was
washed with water and ethanol alternately and then the solvents were
completely evaporated by means of a vacuum drying apparatus to obtain a
dry gel polymer. The powdery gel was comminuted by use of Meteor Rotary
Mill LA-P0 (available from Ito Manufacturing Co., Ltd.), to obtain gel
polymer powder with a peak particle size of about 15 microns. This powder
was dispersed in a 10% ethanol aqueous solution and the dispersion was
held in a sufficient equilibrium.
Next, copper phthalocyanine (available from Dainichiseika Color &
Chemicals) in a 10% ethanol aqueous solution was charged into 01 Attritor
(available from Mitsui Miike) and were subjected to milling for about 20
hours by use of steel balls having a diameter of 0.8 mm, at a rotor speed
of 300 rpm, to prepare a pigment dispersion. This pigment dispersion was
dispersed into the aforementioned gel. Finally, the resulting dispersion
was admixed with 5 ml of 4% KCl aqueous solution, as a response
accelerator, and thus a developer was prepared.
(2) Evaluation of image and the stability in repetitive use
The obtained developer was placed in the recording apparatus and the
evaluation of image was conducted in the same manner as in Example 1. The
image transferred onto a recording paper was clear and free of bleeding
and fogging of the back. Further, images on 3,000 A4 size papers were
prepared consecutively at a rate of 60 images per minute in the direction
of length of A4 size. After that, the images were evaluated, to find
entirely no deterioration of the image.
Example 3
The fine resin particles of the following composition were prepared. A
recording component to the fine resin particles were added thereto, to
obtain an image forming material. The image forming material was subjected
to the evaluation of image, viscosity measurement and evaluation of the
stability of image in repetitive use in the same manner as in Example 1
except that the applied voltage was changed.
(1) Preparation of fine resin particles and image forming materials
______________________________________
1. N-vinyl isobutyl amide
50 parts
2. N-vinyl acetamide 32 parts
3. methacrylic acid 15 parts
4. N,N-methylene bisacrylamide *1 2 parts
5. Tetramethylethylenediamine *2 1 part
______________________________________
(*1: crosslinking agent, *2: polymerization promoter)
The above monomers were dissolved in 140 ml of water. An ammonium
persulfate solution, which had been prepared by dissolving 0.1 part of
ammonium persulfate in 1 ml of water, was combined with the
above-described monomer solution and the resulting solution was vigorously
stirred. The solution thus prepared was dripped into a solution comprising
75 ml of toluene, 25 ml of chloroform and 1 ml of sorbitan trioleate, and
the resulting solution was vigorously stirred in an atmosphere of
nitrogen. After being stirred for 90 minutes at 70.degree. C., 100 ml of
hexane was added to the solution and the solution was stirred again. The
solution separated into two layers, the aqueous layer of which was
collected. 100 ml of hexane was added to the aqueous solution and the
solution was washed under agitation. This washing operation was repeated
three times. After the last wash, the hexane was evaporated by means of an
evaporator, to obtain a slurry gel. The gel was washed with water and
ethanol alternately and then the solvents were completely evaporated by
means of a vacuum drying apparatus to obtain a dry gel polymer. The
powdery gel was comminuted by use of Meteor Rotary Mill LA-)P0 (available
from Ito Manufacturing Co., Ltd.) to obtain gel polymer powder with a peak
particle size of about 7 microns. This powder was dispersed in a 10%
ethanol aqueous solution and the dispersion was held in a sufficient
equilibrium.
Next, 1% Acid Blue 9 (available from Mitsubishi Chemical Corp.) aqueous
solution was prepared and this solution was dispersed into the
above-described gel. Finally, the resulting dispersion was admixed with 5
ml of 10% polyethylene glycol alkyl ether aqueous solution, as a response
accelerator, and thus a developer was prepared.
(2) Evaluation of image and the stability in repetitive use
The obtained developer was placed in the recording apparatus of FIG. 1. An
image was formed on the photosensitive body by carrying out the exposure
according to the condition, i.e., wavelength: 660 nm and light exposure
amount: 0.4 J/cm.sup.2, while applying a voltage of +250 V between the
developer holding roll and the light-transmissive electroconductive layer.
The image was transferred to a sheet of recording paper. The transferred
image was clear and free of bleeding and fogging of the background.
Further, images on a 3,000 A4 size papers were prepared consecutively at a
rate of 60 images per minute in the direction of length of A4 size. After
that, the images were evaluated to find entirely no deterioration of the
image.
Example 4
The fine resin particles of the following composition were prepared. A
recording component was added to the fine resin particles, to obtain an
image forming material. The image forming material was subjected to the
evaluation of image, viscosity measurement and evaluation of the stability
of image in repetitive use in the same manner as in Example 2.
(1) Preparation of fine resin particles and image forming materials.
______________________________________
1. N,N-dimethyl acrylamide 82 parts
2. Vinylbenzyl trimethylammoium chloride 15 parts
3. N,N-methylene bisacrylamide *1 2 parts
4. Tetramethylethylenediamine *2 1 part
______________________________________
(*1: crosslinking agent, *2: polymerization promoter)
The above monomers were dissolved in 140 ml of water. An ammonium
persulfate solution, which had been prepared by dissolving 0.1 part of
ammonium persulfate in 1 ml of water, was combined with the
above-described monomer solution and the resulting solution was vigorously
stirred. The solution thus prepared was dripped into a solution comprising
75 ml of toluene, 25 ml of chloroform and 1 ml of sorbitan trioleate, and
the resulting solution was vigorously stirred in an atmosphere of
nitrogen. After being stirred for 90 minutes at 70.degree. C., 100 ml of
hexane was added to the solution and the solution was stirred again. The
solution separated into two layers, the aqueous layer of which was
collected. 100 ml of hexane was added to the aqueous solution and the
solution was washed under agitation. This washing operation was repeated
three times. After the last wash, the hexane was evaporated by means of an
evaporator, and a slurry gel was obtained. The gel was washed with water
and ethanol alternately and then the solvents were completely evaporated
by means of a vacuum drying apparatus to obtain a dry gel polymer. The
powdery gel was comminuted by use of a Meteor Rotary Mill LA-P0 (available
from Ito Manufacturing Co., Ltd.) to obtain gel polymer powder with a peak
particle size of about 10 microns. This powder was dispersed in a 10%
ethanol aqueous solution and the dispersion was held in a sufficient
equilibrium.
Next, 1% Rhodamine B (available from Mitsubishi Chemical Corp.) aqueous
solution was prepared and this solution was dispersed into the
above-described gel. Finally, the resulting dispersion was admixed with 5
ml of 10% polyethylene glycol alkyl ether aqueous solution, as a response
accelerator, and thus a developer was prepared.
(2) Evaluation of image and the stability in repetitive use
The obtained developer was placed in the recording apparatus of FIG. 1. An
image was formed on the photosensitive body by carrying out the exposure
according to the condition, i.e., wavelength: 660 nm and light exposure
amount: 0.4 J/cm.sup.2, while applying a voltage of -250 V between the
developer holding roll and the light-transmissive electroconductive layer.
The image was transferred to a sheet of recording paper. The transferred
image was clear and free of bleeding and fogging of the background.
Further, images on 3,000 A4 size papers were prepared consecutively at a
rate of 60 images per minute in the direction of length of A4 size. After
that, the images were evaluated to find entirely no deterioration of the
image.
Example 5
An image forming material was prepared by use of the following composition.
The image forming material was subjected to the evaluation of image,
viscosity measurement and evaluation of the stability of image in
repetitive use in the same manner as in Example 1.
______________________________________
1. C.I. Pigment Red 122 2.5 parts
2. the gel polymer prepared in Example 1 50 parts
3. glycerin 2 parts
4. diethylene glycol monobutyl ether 5 parts
5. colloidal silica 10 parts
6. water balance
______________________________________
The obtained developer was placed in the recording apparatus of FIG. 1. The
evaluation of image was then conducted in the same manner as in Example 1.
The transferred image was clear and free of bleeding and fogging of the
background. Further, images on 3,000 A4 size papers were prepared
consecutively at a rate of 60 images per minute in the direction of length
of A4 size. After that, the images were evaluated to find entirely no
deterioration of the image.
Comparative Example 1
A developer was prepared in the same manner as in Example 5 except that an
ammonium salt of a styrene/maleic acid copolymer was used in place of the
polymer employed in Example 5. The image forming material was subjected to
the evaluation of image and viscosity measurement in the same manner as in
Example 1. The obtained image exhibited a markedly foggy background and
remarkable bleeding of image even at the initial state.
Comparative Example 2
A developer was prepared in the same manner as in Example 5 except that
polyvinyl alcohol (having a degree of polymerization of 2,000) was used in
place of the polymer employed in Example 5. The image forming material was
subjected to the evaluation of image and viscosity measurement in the same
manner as in Example 1. The obtained image exhibited a markedly foggy
background and remarkable bleeding of image even at the initial stage.
TABLE 1
______________________________________
Viscosity of the
Developer before the developer after the
application of application of
electric energy electric energy
______________________________________
Example 1 solid (gel) 1.2 .times. 10.sup.2 mPas
Example 2 solid (gel) 1 .times. 10.sup.2 mPas
Example 3 solid (gel) 2 .times. 10.sup.3 mPas
Example 4 solid (gel) 8 .times. 10.sup.1 mPas
Example 5 solid (gel) 5 .times. 10.sup.2 mPas
Comparative solid (gel) 1 .times. 10.sup.5 mPas
Example 1
Comparative solid (gel) >1 .times. 10.sup.5 mPas
Example 2
______________________________________
As is apparent from the description of the Examples, the image forming
materials of the present invention exhibited a rapid and reversible
fluidization by the application of electric energy. The image forming
materials of the present invention were free of the image defects, i.e.,
the fogging of the background and bleeding of the image, which were
associated with the electroconductive wet-process developers utilizing
conventional water-based developers and with the image making method
utilizing such developers and which are indicated in Comparative Examples
1 and 2. Further, the image forming materials of the present invention
made it possible to form the image rapidly, and to form the image in a
stable manner without presenting any deterioration in the image quality
even after repetitive use.
Besides, the aforementioned Examples could provide safe developers, because
these were based mainly on water as solvent and were free of the
environmental pollution to which the conventional wet-process developers
were linked.
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